Lapping machine



Dec. 14,1926. v J. N. BETHEL LAPPING MACHINE File d Feb. 2. 292: v

2 Sheets-Sheet fiderzf @cpfa Patented Dec. 14, 182$.

JOSEPH 1v. IBE'IHEL, or wono'nsrna, MASSACHUSETTS, ASSIGNOR 'roBETHEL-PLAYER co, or WESTBORO, MASSACHUSETTS, A. COPARTNERSHIPconsrs'rnxre or JOSEPH 1v.

BETHEL AND SIDNEY K11 521113.

nar rrivs MACHINE" Application filed February 2. 1 923. ,.Seria1 No.616,474.

1 This invention relates to a machine for lapping steel bushings, studsor rolls or other articles'whi'ch are'to be brought quickly to accurateand uniform size.

Itis the object of my invention to improve the construction ofsuch'lappin'g machines so that more accurate work canbe obtained andthatthe cost of producing such accurate ture relates to the provision ofmeans forvarying the eccentricity of the bearing member.

My invention further includes means for vertically adjusting the upperor fixed lap in the machine, said means permitting removal of the fixedlap from operative position in a horizontal direction while maintainingthevertical position thereof. I also disclose herein variousarrangements and combinations of parts which will be herein afterdescribed and more specifically pointed out in the appended claims.

A preferred form of my invention is shown in the drawings in which Fig.1 is a front elevation of my improved machine, with-certain parts shownin section;

Fig. 2 is an enlarged sectional elevation of the driving mechanism forthe lower lap and eccentric work holder bearing member;

Fig.8 is a partial plan view of a work holder;

Fig. 4 is a plan view of the upper end of the eccentric bearing supportand its driving shaft; I

Fig. 5 is a plan view of the adjustable eccentric bearing member andplate; I

Figs. 6 and 7 are a plan and side elevation respectively of a portion ofone of the work holding arms; 7

Fig. 8 is a Side elevation of one of the work retaining collars; and

Fig. 9 is a detail sectional view showing the lost motion connection ofthe fixed lap. Referring to Fig. 1, I have shown alapping machinecomprising a base 10 on which is mounted a post or standard 11 having acollar 12 which may be clamped, thereto in any desired verticalposition. "Aridarm 13 has 'a' split hub or bearing portion 14v alsomounted on the;post 11 and held in adjusted vertical position by thecollar 12. The arm 13 may be swung in a horizontal plane about the axisof the post 11 and may be clamped in any desired position by upper andlower clamping devices 15 and 16.

At itsouter end, the arm 13 supports a sleeve 17 within which a rack bar18 is slidably mounted. The rackpbar 18' is engaged by a pinion (notshown) ona cross shaft 19v mounted in hearings on the arm 13 and havinga hand wheel 20 for rotation thereof.

A locking pawl 21 is pivoted on the arm 13 and engages a ratchet wheel22 fixed to the shaft 19; by which action the rack bar 18 may be held inany desired vertical position.

A spider or head 23 on the lower end-of the rack bar 18 supports thenon-rotatable lap. 24. The head 23 is preferably loosely fitted on thebar 18 (see' Fig. 9) to permit slight rocking movement relative to thebar 18 so that the lap 24 may angularly adjust itself to the surface ofthe work rotating beneatlr the lap. The head 23 and lap 24 are held fromrotation by a suitable connection to the rack bar 18 which is of suchform that the free rocking movement of the head is not interfered with.

The lower or rotatable lap 25 is mountedon a hub or flange 26 which iskeyed to a hollow shaft or sleeve '27 rotatable in up per and lowerfixed bearings 28 and 29 in the frame 10. A worm wheel 30'is fixed tothesleeve 27'and is engaged by-a worm 31 on a drive shaft 32 The shaft .32rotates in bearings fixed inthe frame 10 and is provided with tight andloose pulleys '33 and 34 for the usual belt drive (not shown).

An eccentric pin or hearing member 40 (Fig. 2) .is fixed on a slottedplate 41 (Fig. 5) which is transversely adjustable in guide ways 42(Fig. 4) in a plate or disc'43 selcured' to the upper end of a shaft 44freely rotatable in bearings'within the lap-driving sleeve 27. The plate41 is secured in adjusted position in the guide ways 42 by a bindingscrew 45 at the upper end of the shaft 44.

A differential gear drive i provided he tween the sleeve 27 and theshaft 44. For this purpose a gear 46 on the lower end of the sleeve 27engages a pinion 48 rotatable on a fixed stud 49 and having a slightlysmaller pinion 50 mounted to rotate therewith. gear 51 on the lower endof the shaft 44. By these connections the shaft 44 is driven at adifferential speed from the sleeve 27 which rotates the lap 2:3. Thecombination of gearing shown in the drawings provides a speed for theshaft 44 slightly slower than that of the lap 25. Under certainconditions it might be desirable to reverse the gearing shown in Fig. 1,thus driving the shaft 44 at a sligl'itly increased speed.

A work holder is mounted for free rotation on the eccentric pin orbearing mem her 40 (Fig. This work holder may he of any form adapted-tothe work to be lapped and as shown herein comprises a disc or plate 53having a plurality of arms 54 extending outward therefrom and preferablyat an acute angle to the adjacent radii. This form of holder is adaptedfor supporting the cylimlrical sleeves or bushings S which are shown inFigs. 2 and 3. The arms are preferably provided with ]on gitudinalgrooves 55 and transverse notches 56 and are adapted to receive lockingcollars 57 each having a stud 58 extending within the collar. Thesecollars may be quickly placed in position by sliding the studs 58 alongthe grooves 55 to the desired position and thereafter turning thecollars so that the studs will enter selected notches The work holder 52is thus readily adapted to bushings of different lengths. This form ofholder is illustrative only and in itself forms no part of my invention,which merely requires that the work holder be freely rotatable upon thepin or bearing Having described the construction of my improved lappingmachine, the method of operation will be easily apparent. The work S isplaced upon the arms 54 of the work holder 52 which is then mounted onthe occentric bearing member 40, with the work resting freely upon theupper surface of the rotatable lap The upper lap 24 is then lowereduntil it engages the upper surface of the work, after which the machineis started and the lap 25 is positively rotated.

The eccentric pin or bearing 40 will also 'be positively rotated but ata slightly different speed and will give an eccentric motion to thecenter of the work holder 52 without imparting any positive rotationthereto.

The pinion 50 engages a release construction the Work is caused toengage every portion of the surface of both the fixed and movable la 5and the differential eccentric motion has een found to possess veryimportant advantages, particularly in respect to eliminating flat spotson cylindrical work. The work produced by this machine has been foundgreatly superior in this respeetto work produced by a similar machine inwhich the eccentric pin was driven at the same speed as the 'rotatalj lelap.

Having thus described my invention ,and the advantages thereof. I do notwish to be limited to the details herein disclosed oth-' erwise than asset forth in the claims, but what I claim is? 1. A lapping machinehaving, in combination, a fixed lap, a positively rotated lap, meansincluding an outer driving sleeve for rotating said lap, an eccentricbearing member mounted'to rotate about the axis of said rotatedv lap, aninner driving shaft for'said eccentric bearing member rotatablysupported in bearings within said outer driving sleeve, and positivedriving-eonnections"be tween said outer driving sleeve and said innerdrivin shaft effective to rotate said shaft simultaneously therewith butat a different speed.

2. A; lapping machine having, in combination, a fixed lap, a positivelyrotated lap, means incluing an outer driving sleeve for rotating saidlap, an eccentric bearing member mounted to rotate about the axis ofsaid rotated lap, aninner driving shaft for said eccentric bearingmember rotatably supported in bearings within said outer driving sleeve,and positive driving connections between said outer driving sleeve andsaid inner driving shaft effective to rotate said shaft simultaneouslytherewithin the same direction but at a different speed.

3. A lapping machine having, in combina tion, a fixed lap, a positivelyrotated lap, means including an outer driving sleeve for rotating saidlap, an eccentric bearing member mounted to rotate about the axis ofsaid rotated lap, an inner-driving shaft for said eccentric bearingmember rotatably supportecLin bearings within said outer driving sleeve,gears on .the lower ends of said driving sleeve and said inner shaft,and a pair oftransmitting gears secured together and rotatable about anaxis parallel to the axis of said sleeve and meshing with saidfirstmentioned gears to cause rotation of said shaft at a speeddifferent from the speed of said sleeve but in fixed relation thereto.

4. A lapping machine having, in combination, a fixed lap, a positivelyrotated lap, an eccentric bearing member mounted on a support to rotateabout the axis of said rotated lap, positive differential gearingbetween said rotated lap and said eccentric bearing support, and a workholder freev member.

ly rotatable about said eccentric bearing I 5. A lapping machine having,in combination, a fixed lap, a positively rotated lap, an eccentricbearing member mounted to rotate about the axis of said rotated lap, apositive differential gear drive between said eccentric bearing supportand said rotated lap. a work holder freely rotatable about saideccentric hearing member, and means to vary and adjust the eccentricityof said eecentric bearing member,

6. A lapping machine comprising a rotatable lower lap, 21 non-rotatableupper lap, means to raise and lower said upper lap, means to move saidupper lap horizontally to and from operative position, means to holdsaid upper lap in horizontally adjusted position, and means tomaintainsaid upper lap at a fixed elevation during such horizontalmovement.

7. A lapping machine having a rotatable lower lap; at non-rotatableupper lap, means to rotate said lower lap, an a' rack bar supportingsaid upper lap, said bar and lap being loosely connected to permitlimited equalizing movement of said upper lap while preventing rotationthereof. W

.In testimony whereof I have hereunto at fixed my signature.

[JOSEPH N. BETHEL.

